U.S. patent number 5,494,720 [Application Number 08/297,303] was granted by the patent office on 1996-02-27 for seams and closures for plastic fabrics and clothing.
This patent grant is currently assigned to Lakeland Industries, Inc.. Invention is credited to Peter Holemans, W. Novis Smith.
United States Patent |
5,494,720 |
Smith , et al. |
February 27, 1996 |
Seams and closures for plastic fabrics and clothing
Abstract
A heat sealable, adhesive-free seam and closure fabrics and
clothing comprising the combination of a fabric scrim and a heat
sealable water and vapor resistant coextruded laminations which
provides a barrier against liquid substances and vapors. The
coextrusion laminations are in abutment or overlap and comprise a
film layer with an outer and inner layer of low density
polyethylene and an intermediate layer of a copolymer of ethylene
and vinyl alcohol. The laminations are fusion bonded to a portion
of the scrim in a manner whereby the polyethylene flows from said
lamination, encapsulates the ends of the intermediate layer of the
laminate and forms weld points with the said scrim to prevent
penetration by liquid substances and vapors.
Inventors: |
Smith; W. Novis (Philadelphia,
PA), Holemans; Peter (Philadelphia, PA) |
Assignee: |
Lakeland Industries, Inc.
(Ronkonkoma, NY)
|
Family
ID: |
23145745 |
Appl.
No.: |
08/297,303 |
Filed: |
August 29, 1994 |
Current U.S.
Class: |
428/57;
2/275 |
Current CPC
Class: |
A41D
27/24 (20130101); B29C 66/72341 (20130101); B29C
66/43 (20130101); B29C 66/1122 (20130101); B32B
7/12 (20130101); B29C 66/71 (20130101); A41D
27/245 (20130101); B29C 65/02 (20130101); B32B
27/306 (20130101); B32B 27/12 (20130101); B29C
66/72343 (20130101); B32B 27/32 (20130101); B32B
27/08 (20130101); B29C 66/45 (20130101); B29C
66/71 (20130101); B29K 2023/086 (20130101); B29C
66/71 (20130101); B29K 2023/0633 (20130101); B32B
2323/04 (20130101); B32B 2262/0284 (20130101); B29C
66/124 (20130101); B29C 65/4815 (20130101); B29L
2031/52 (20130101); B32B 2262/0261 (20130101); B29C
65/50 (20130101); B32B 2307/7265 (20130101); Y10T
428/19 (20150115); B32B 2307/7242 (20130101); B32B
2262/0253 (20130101); B29L 2031/4842 (20130101); B29C
65/08 (20130101); B32B 2323/046 (20130101); B29C
66/729 (20130101); B32B 2329/04 (20130101); B29L
2009/00 (20130101); B29C 66/71 (20130101); B29K
2079/00 (20130101); B29C 66/71 (20130101); B29K
2077/00 (20130101); B29C 66/71 (20130101); B29K
2067/003 (20130101); B29C 66/71 (20130101); B29K
2033/20 (20130101); B29C 66/71 (20130101); B29K
2023/00 (20130101) |
Current International
Class: |
A41D
27/24 (20060101); A41D 27/00 (20060101); B29C
65/00 (20060101); B32B 27/12 (20060101); B32B
003/06 () |
Field of
Search: |
;428/57,58,61 ;2/275
;112/440,441 |
Primary Examiner: Thomas; Alexander S.
Attorney, Agent or Firm: Lezdey; John
Claims
What is claimed is:
1. A heat sealable seam for plastic fabrics and clothing comprising
the combination of a fabric scrim and a heat sealable water and
vapor resistant coextruded lamination which provides a barrier
against liquid substances and vapors, said lamination being in an
abutting or overlapping relationship and comprising outer and inner
film layers of low density polyethylene and an intermediate film
layer of a copolymer of ethylene and vinyl alcohol, said film
layers being fusion bonded to each other to form said lamination,
which is fusion bonded to said scrim, where in the polyethylene
flows from said lamination, encapsulates portions of said
intermediate layer and forms weld points with said scrim to prevent
penetration by liquids and vapors.
2. The seam of claim 1 wherein a further layer of a low density
polyethylene layer is adhesively bonded to said scrim.
3. The seam of claim 1 which is a butt seam.
4. The seam of claim 1 wherein low density polyethylene is fusion
bonded over the edge of said lamination and said scrim.
5. The seam of claim 1 wherein said low density polyethylene has a
softening point of about 250.degree.-350.degree. F.
6. The seam of claim 1 wherein said scrim comprises high tensile
fibers selected from the group consisting of polyethylene
terephthalate, polyolefins, poly p-phenylene terephthalamide, poly
m-phenylene terephthalamide, carbonaceous polymeric oxidized
polyacrylonitrile, nylon, polybenzimidazole and mixtures
thereof.
7. A garment fabricated in part with the seam of claim 1.
8. The seam of claim 1, wherein said seam is free of adhesives.
Description
FIELD OF THE INVENTION
The invention relates to heat sealable, adhesive-free high strength
seams and closures for plastic fabrics. More particularly, the
invention is concerned with heat sealable, adhesive-free seams and
closures in combination with fabrics comprising laminates of an
inner and outer film layer of a low density polyolefin or ethylene
vinyl acetate and an intermediate film layer comprising cellulose
acetate, ionomer the copolymer of ethylene and vinyl alcohol, or
nylon and clothing or articles made therewith.
BACKGROUND OF THE INVENTION
Protective clothing and containers of many types is well known for
many and varied uses including protection from fire, vapors and
harmful substances. Such clothing is often seen in suits for
industrial workers, firemen, hazardous waste workers, race car
drivers, airplane pilots and military personnel. Garments include
not only complete hermetic suits, but also individual components
such as trousers, jackets, gloves, boots, hats, head coverings,
masks, etc.
Regulations restricting exposure to hazardous environments of
various kinds, such as those contained in the Occupational Safety
and Health Act, make it increasingly necessary to have better and
more effective kinds of protective clothing. In particular, certain
requirements by the U.S. Coast Guard and related requirements by
other U.S. government agencies involve a total protective hermetic
suit or envelope around the individual person to protect the worker
from the widest possible range of hazardous materials.
Encapsulating suits are necessary for "immediately dangerous to
life and health" (IDLH) environments. These suits must be air tight
and worn with a self-contained breathing apparatus. The suit must
be nonabsorbent, totally impermeable, and resistant to the widest
range of chemicals and reagents. It should also be as fire
resistant as possible. Since these suits are being worn by active
individuals, they should also be flexible, abrasion resistant,
lightweight, and should maintain their impermeability while being
used. Such suits are commonly called "HAZ MAT" suits with class A
level being the most vapor proof.
The garments presently available are almost invariably of thick
construction and heavy in weight, and are often fabricated at least
in part from materials impermeable to water or water vapor, such as
natural and synthetic rubbers and elastomers, chlorinated rubbers,
etc.
Protective clothing comprised of laminates of films have the
problem of forming kinks when bent. This restricts motion and makes
movement cumbersome. Moreover, much of the protective clothing is
porous and provides little protection against hazardous chemical
vapors.
It is therefore desirable to utilize an impermeable fabric which
possesses heat sealing properties and is resistant to a large range
of chemicals. Sewn seams are permeable to chemical vapors, whereas
heat fused seams are impermeable. Even seams put together with
adhesive (hot melt or pressure sensitive) can pull apart or be
undercut by vapors.
The optimum sealing of seams, which join the various pieces of
laminated fabric to form a protective suit against chemical vapors
have a seam that is equal to or better than the laminate fabric
against permeable chemical vapors. Therefore, it is preferred to
have a laminated fabric which heat seals to itself so that a tape
related to the barrier films can be used to heat seal the seam and
give excellent chemical protection.
U.S. Pat. No. 4,515,761 to Plotzker describes a protective garment
for use in detoxification which contains a layer of a highly
fluorinated ion exchange polymer having sulfonic acid multivalent
metal ion salt functional groups.
SUMMARY OF THE INVENTION
In accordance with the present invention, a novel seam sealing,
vapor and liquid resistant laminate, and a method for sealing
without the use of adhesives, is employed for clothing, including
raincoats and protective clothing, boots, containers, etc. The seam
sealing laminates comprise a first and second laminate of an outer
and inner film layer each of which consists of a low density
polyethylene and an intermediate layer of an ionomer, nylon,
cellulose acetate or a copolymer of ethylene and vinyl alcohol.
Preferably, the polyethylene has a softening point of about
250.degree.-350.degree. F. The laminates are both water and
chemical resistant. The polyethylene layers weld together to form a
lap or butt seam and the intermediate layers provide the protection
against breakthrough. Bonding a scrim layer with welds from the
polyethylene provides the strength for the seam.
Accordingly, the invention provides a heat sealable water and
chemical resistant seam sealing laminate or coextrusion for use in
forming protective clothing such as rainwear, chemically protective
garments, and the like. The said laminates or coextrusions comprise
a film layer with an outer and inner layer of low density
polyethylene which creates the bond and an intermediate layer which
provides the chemical resistance. The seam is formed by the
laminates overlapping or being in abutment. The polyethylene forms
a fusion bond between the laminates and the scrim. That is, the
polyethylene flows and encapsulates the overlapping or abutting
portions as well as forms weld points with the scrim. The seam may
be capped with polyethylene which is adhesively a fusion bonded to
the seam.
As a support for the laminates, a fabric is fusion bonded by the
flowable molten low density polyethylene. The fabric is preferably
comprised of high tensile fiber selected from the group consisting
of polyethylene terephthalate, polyolefin poly p-phenylene
terephthalamide, poly m-phenylene terephthalamide, carbonaceous
oxidized polyacrylonitrile, nylon, rayon, cotton and
polybenzimidazole or blends thereof to provide strength to the
seam.
In accordance with another embodiment of the invention, a method is
provided for forming and seam sealing a plastic facepiece such as
fluorinated ethylene polyethylene copolymer (FEP) or perfluoralkoxy
resin (PFA) onto a plastic garment. The method comprises the steps
of
A. applying a gasketing compound along the edges of a plastic film
suitable for use as a facepiece;
B. placing the facepiece against a laminated fabric which comprises
the same material as the seam sealing laminate of the
invention;
C. sewing through the laminate and the facepiece to strongly attach
the components together;
D. heat sealing film over the holes of the top and bottom of the
seam with an appropriate tape to form the headpiece of the garment;
and
E. (optional) capping over the seam portion with a chemical
resistant strip which bonds to the polyethylene either alone or
with an adhesive.
The capping over may be performed by adhesively bonding a suitable
chemical resistant strip, such as FEP tape or the laminate used in
the invention.
This approach can be used for seam sealing any dissimilar material
to the suit such as facepieces or zippers.
In order to maximize the impermeability of the fabric seam against
all liquid substances and vapors, laminates forming the seam must
be composed of a coextrusion or laminate which includes an ionomer,
cellulose acetate, nylon or the copolymer of ethylene and vinyl
alcohol sandwiched between two chemical resistant layers of low
density polyethylene. Additionally, the film itself must be without
pin holes, outer fibers or porosity which lessen the barrier
resistance of the actual film. Fusion bonding a continuously formed
laminate to a fabric gains the strength of the woven or non-woven
fabric without interfering with barrier properties of the film. It
enhances the resistance to flex cracking, wrinkles and failure from
tearing and bursting to the total laminated fabric. Because of the
absolute fail-safe requirements of chemical protective clothing and
the need for easily putting the suit on or taking it off, an inner
layer of film should also be used to form a sandwich with the
fabric. This maximizes the flexibility of a given construction with
the total plastic film barrier being split into two layers and
being easier to flex than one thick layer.
Furthermore, it is essential that the seams throughout the garment
as well as along a facepiece be resistant to failure, so that they
are melt fusion bonded, preferably with additional tape similar to
the actual fabric film. It is critical in the invention that a low
density polyethylene be utilized since medium and high density
polyethylene do not possess the heat sealing features necessary for
the invention.
The sealing with the low density polyethylene can occur at lower
temperatures than most plastics using heat and pressure or by
ultrasonic bonding.
The laminate of the invention can be used to produce chemical and
weather protective clothing as well as containers. Embossing the
laminates of the invention improves their flexibility as well as
the strength of the laminate.
In accordance with another embodiment, the invention provides a
self heat sealing fabric seam for clothing, containers and covers
for protection against liquids and vapors. More particularly, the
fabric seam is provided with an outer layer comprising a
coextrusion or laminate of a copolymer of ethylene and vinyl
alcohol (EVOH) sandwiched between a polyolefin or ethylene vinyl
acetate layer, an intermediate layer of a fabric, preferably of
high tensile fibers and a film layer bonded on the inner surface of
the fabric comprising either the seam sealing laminate or a
polyolefin film. The ethylene-vinyl alcohol copolymer inner layer
can comprise the copolymer itself or it can comprise a layer of the
ethylene-vinyl alcohol copolymer extruded with one or more layers
of a polyolefin, for example, polyethylene, polypropylene and the
like or an ionomer, for example ethylene-vinyl alcohol copolymer,
and the like. Another version of this fabric seam uses only one
layer of film bonded to the scrim.
The invention also relates to impermeable seams and closures in
garments, rainwear, containers and covers which are fabricated in
part from the fabric of the invention.
Other objects and a fuller understanding of the invention will be
had by referring to the following description and claims taken in
conjunction with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a exploded sectional view of the coextrusion or laminate
film of the invention,
FIG. 2 is a sectional view illustrating the laminate of the
invention,
FIG. 3 is a sectional view illustrating an alternative laminate of
the invention,
FIG. 4 illustrates a protective garment with the seal and fabric of
the invention, and
FIG. 5 is a sectional view of the seam of the invention of the
invention, and
FIG. 6 is a sectional view of an alternative way for the seam of
the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Although specific terms are used in the following description for
the sake of clarity, these terms are intended to refer only to the
particular structure of the invention selected for illustration in
the drawings, and are not intended to define or limit the scope of
the invention.
As shown in FIG. 1, there is provided a laminate 10 comprising an
outer film layer 11 and an inner film layer 13 consisting of a low
density polyethylene coextruded with an intermediate film layer 12
containing the ethylene-vinyl alcohol copolymer layer. The laminate
is suitable in the form of strips to act as seam sealers by
thermally bonding to a garment or in forming a zipper strip. Other
film layers may be included along with the EVOH but it is critical
that the outer layers be a low melting version of polyethylene or
its copolymers.
FIG. 2 shows a laminate 15 which is formed with the laminate 10 of
FIG. 1. Laminate 15 comprises a top layer 11 of low density
polyethylene bonded to the copolymer 12 of ethylene and vinyl
alcohol which in turn is bonded to a further layer 13 of low
density polyethylene. The laminate 10 is advantageously fusion
bonded to a scrim of a non-woven, woven or knitted fabric 16 which
preferably comprises a high tensile strength material. Fusion
bonding by heat and pressure or ultrasonic bonding with added
molten low density polyethylene or EVA causes the polyethylene
layer 13 to flow and encapsulate portions of the fabric 16 with
weld points 13a so as to provide additional strength to the overall
structure. Further heat or ultrasonic bonding with added molten low
density polyethylene or EVA form an additional layer 17 with the
developed weld point 17a. Weld point 17 may be the same film as
laminate 15 or a low density polyethylene layer. The laminate 10
may constitute just the laminate 15 bonded to the fabric as in FIG.
3. The formed laminate 15 can comprise the entire protective
garment or function as a seam sealer.
Alternatively, the laminate 10 can be bonded to the fabric 16 to
form a laminated fabric. However, to maximize the impermeability of
the fabric against toxic vapors and to provide heat sealability to
both sides of the laminated fabric, a further layer 17 is bonded to
laminate 10 or a further low density polyethylene film layer is
bonded to the fabric 16. An adhesive bond provides greater
flexibility than fusion bonding for this layer. However, there
should be no seams in the outer shell which is adhesively bonded.
Advantageously, the adhesive utilized for bonding to the outer
fabric is fire resistant.
As illustrated in FIG. 4, a protective garment 20 is prepared from
the fabric comprising films with the outer layers of low density
polyethylene. The garment 20 is provided with an optically
transparent facepiece 21 and zipper strip 23. The facepiece 21 and
zipper strip 23 can be formed from thick films of polyvinyl
chloride or a ethylenevinyl alcohol copolymer layer similar to the
film used in the interior of the garment 20. The facepiece 21 can
also comprise a barrier film such as a Teflon (PFA, FEP), nylon,
polyester, or an ionomer which is optically transparent and inert
to many chemicals. Preferably, perfluoroalkoxy resin (PFA) or
fluorinated ethylene polyethylene copolymer (FEP) is used. Suitable
ionomers are described in U.S. Pat. No. 4,799,346, which is herein
incorporated by reference.
The garment 20 is sealed with strips of the laminate 10 or low
density polyethylene along the seams, facepiece 21 and zipper strip
23. Embossments 22 of the strip 10 provides flexibility and
strength to the seams.
The entire laminated fabric can also be embossed to minimize
wrinkling of the suit as well as provide enhanced flexibility and
strength.
FIG. 5 illustrates a method of seam sealing of zippers with
dissimilar materials such as polyvinyl chloride or butyl rubber or
neoprene. The fabric layers 30,30' which consist of the same
structure as the laminate 10 of the FIG. 1 are cut out and sandwich
an intermediate fabric 21 along its edges. A gasketing compound 28,
preferably a siloxane adhesive such as polydimethyl siloxane, is
provided. A thread 26, preferably a high tensile fiber, is sewn
through the layers 30,30' and fabric 21. The layers 30,30' are heat
sealed together along the edges of the fabric 21. The threaded area
is then capped so as to prevent any vapors from penetrating through
pinholes that may exist and to further strengthen the area. This
maybe done from one or both sides. A suitable method of capping
utilizes a strip of a chemical resistant material such as the
laminate 10 of FIG. 1. Alternatively, the strips can be heat sealed
over the area. Heat sealable strips 33, 33' that are compatible
with the material used for the facepiece seal the edges along the
fabric 21.
Alternatively in FIG. 6, the heat sealable laminated fabric seam is
placed only on one side of the dissimilar materials layer. The
gasketing compound 28 is placed between the sewn seam. The outer
seam holes are capped with a heat sealable film 27. The inside
holes are heat sealed with a compatible tape, such as, FEP or PFA
sealing tape for an FEP or PFA window. In those cases where a heat
sealable tape is not available, then a hot melt tape is sealed over
the seams. Optionally, an FEP pressure sensitive tape 33,33' can be
applied over the back seam holes and along the edges where the two
layers overlap 33,33'.
The thickness of the polyethylene films is generally in the range
of about 0.8 to 10 mils. The total thickness of the laminate 10 is
generally about 10-30 mils. The ethylene-vinyl alcohol copolymer
preferably contains about 20 to 70% vinyl alcohol, although, it can
also contain ionomer residues.
The ethylene vinyl alcohol copolymer layers in the coextrusion
films or laminates range in thickness from about 0.1 to 2.0 mils
and can comprise one or more layers. The overall thickness of these
co-extruded films is preferably about 2 to 10 mils depending upon
the ultimate use. Generally, the other resin layers are
polyethylene, nylon or SURLYN (ionomer) in addition to the
ethylene-vinyl alcohol copolymer layer.
The intermediate fabrics 16 which are used in making the laminated
fabric 18 are many and varied. They can be, but are not limited to
cotton, KEVLAR, NOMEX, PBI, rayon, wool, silk, polyester, nylon,
polyethylene, polypropylene or other high tensile strength
fibers.
The high tensile strength fibers which may be utilized to prepare
the fabric layer 16 of the present invention include polyamides
such as poly (m-phenylene isophthalamide), poly (p-phenylene
terephthalamide) KEVLAR, poly (m-phenylene terephthalamide), NOMEX,
nylon, polyolefins, polyethylene terephthalate (PET), carbonaceous
polymeric materials such as those described in U.S. Pat. No.
4,837,076, polybenzimidazole, oxidized polyacrylonitrile fibers and
blends thereof.
The intermediate fabric 16 includes plain and upstop weaves and
knitted, non-woven, felted, spun bonded, melt spun or porous
fabric. Preferably, the fabric is fire resistant. The intermediate
fabric 16 must provide high flexibility, tear strength and
resistance to cracking and wrinkling. It must prevent damage to the
inner film layer in the event the outer film is punctured so as to
prevent exposure by the wearer to toxic chemicals.
The fabric 16 can be bonded to the outer films by an adhesive,
preferably a flexible adhesive. Preferable adhesive compositions
include ethylenevinyl acetate, low melting polyolefins, urethanes,
polyesters, and ethyleneacrylic ester copolymers such as described
in U.S. Pat. No. 4,322,516, which is incorporated herein by
reference. Pressure sensitive, thermoset and hot melt adhesives may
be used. It is also desirable that this adhesive be fire resistant
in appropriate cases. It is critical that all outer seams are
formed by fusion bonding.
Although the invention has been described with preferred
embodiments, it is understood that variations and modifications may
be employed without departing from the concept of the invention as
defined in the following claims.
* * * * *